High frequency switching unit



Feb. 9, 1 960 D. H. LANCTOT 2,924,677

HIGH FREQUENCY SWITCHING UNIT Filed Nov. 20, 1958 3 Sheets-Sheet 1INVENTOR. DONALD H. LANCT'OT ATT ORN E YS 1960 D. H. LANCTOT 2,924,677

HIGH FREQUENCY SWITCHING UNIT I Filed Nov. 20, 1958 3 Sheets-Sheet 2'IIIIIIIIIIIJ\ I IN VEN TOR. DONALD H. LANCTOT BY was MZdiu' v AmeusrsFeb. 9, 1960 D. H. LANCTOT 2,924,677

HIGH FREQUENCY swncnmc UNIT Filed Nov. 20, 1958 :s Sheets-Sheet 3 IN VENTOR. DONALD H. LANCTDT BY m fldza' w ATTORNEYS United States Patent2,924,671 HIGH FREQUENCY SWITCHING UNIT Donald H. Lanctot, Malibu,Califl, a'ssignoi to Don-Lan Electronics Co., Inc, a corporation of(Ialifornia Application November 20, 1958, Serial No. 775,250 8 Claims.Cl. 200-24 This invention relates generally to electrical switches andmore particularly to an improved unit for switching high frequencyelectrical energy from an input coaxial line to two or more outputco-axial lines.

Switches of the type under consideration are particularly well adaptedfor switching high power, high frequency electrical energy between twoor more antennas such as employed in radar systems. In certaininstances, there may .be provided a single reflecting type antennastructure fed by two separate co-axial lines. arranged to deliver energypulses alternately to the antenna from different focus points so thatthe beam or lobe from the antenna is shifted between two limits. Inother instances, there may be several antennas which are sequentiallyenergized to'provide an eifective lobe sweeping characteristic.

It is extremely important in all such switches of the foregoing type tominimize losses and noise, provide proper isolation between the variousoutput lines, and maintain a proper impedance match between the inputand the various output lines 'to which the energy is distributed.

Power losses from leakage and poor impedance matching can best beovercome by providing a positive connection in the switching unit as bya metal to metal contact between the various inner conductors of thecoaxial lines. On the other hand, the absence of a metal to metalcontact between the other lines insures excellent isolation. Heretofore,the problem of making and breaking metal to metal contacts between thevarious inner conductors of co-axial lines at a sufficiently high lobingfrequency to be useful, has proven very difiicult. If capacitancecoupling is resorted to, the usual losses across the capacitances areincurred and the various energy portions distributed among the outputlines are not positively defined.

Bearing the foregoing in mind, it is a primary object of the presentinvention to provide a greatly improved type of high frequency switchingunit particularly useful in lobing operations in which the various innerconductors of co-axial lines are positively connected by a metal tometal contact so that discrete and equal or proportioned amounts ofenergy may be distributed between the various lines with a minimum ofelectrical loss and at a desired frequency rate. I

More particularly, objects are to provide an improved lobing switch ofthe foregoing type which is positive and consistentthroughout inoperation, the metal to metal contact points automatically compensatingthemselves for wear, which exhibits excellent isolation between theconnected and disconnected lines, which has a relatively good impedancematch between the connected lines, and which is characterized by highreliability, low noise level, and low maintenance.

Another important object is to provide a switch in which the connectionbetween one output co-axial line and the input line may be made prior tothe breaking of Eatented Feb. 9, 1960 the connection between apreviously connected output co-axial line and the input line.

An auxiliary object to the above object is to provide simple means forenabling the breaking of a connection prior to the making of another sothat the switch finds use in certain applications in which thischaracteristic is desired.

These and many other objects and advantages of this invention areattained by providing a switching unit including a basic metallic blockmember including output connections for receiving the output co-axiallines between which energy is to be switched. An input connector has itsouter conductor connected to this block and its inner conductorprojecting into a central cavity in the block. This inner conductor iscentrally secured in a stationary position within the cavity. The innerconductors of the various output connectors extend laterally throughsuitable bores in the block to terminate short of the stationaryconductor of the input connector. (Io-operating with each of the innerconductors of the output connectors is a conducting sleeve contactorarranged to telescope over the inner conductors and thus be moved intoor out of engagement with the center stationary conductor. Suitablebiasing means normally urge the sleeve contactors towards the stationaryconcluctor.

A drive means including either an insulative or conducting roller isarranged to revolve about the stationary conductor within the cavity ofthe block and sequentially move the contacting sleeves into and out ofengagement with the inner conductor. The roller can be arranged torevolve about the center conductor extremely rapidly so that switchingcan take place at a desired lobing frequency. Further, wear of thecontact surfaces of the various sleeve contactors and central conductorwill be compensated as a consequence of the biasing means continuouslyurging the sleeve contactors towards the central conductor. In apreferred embodiment the central conductor includes secondary springcontacts to avoid chatter and minimize noise upon contact.

A better understanding of the invention will be had by referring to apreferred embodiment thereof as illustrated in the accompanying drawingsin which:

Figure 1 is a cutaway elevational view partly in cross section of thecomplete lobing switch of this invention;

Figure 2 is a cross section of the switch taken in the direction of thearrows 22 of Figure 1;

Figures 3 and 4 are cross sectional views similar to Figure 2, butshowing the movable parts of the switch in different positions.

Figure 5 illustrates in perspective a modified type of center conductor;

Figure 6 is a top plan view of the conductor of Figure 5 in one contactmaking position; and,

Figure 7 is an enlarged fragmentary view of a portion of Figure 1showing a modified roller and sleeve.

Referring first to Figure 1, the switch includes a casing 10hermetically sealed to a metallic block '11. The front face of the block11 is threaded to receive an input co-axial connector 12. Two outputco-axial connectors 13 and 14 are in turn secured to opposite side facesof the block 11. The block 11 connects all of the outer conductors ofthe input and output co-axial connectors together and is normally atground potential.

Housed within the casing 10 is a motor 15 arranged to be energized bysuitable power input leads 16 from an external connector 17. Motor 15includes a shaft 18 extending into a part of the block 11 through asuitable journal bearing 19. The end of shaft 18 is provided with adriving member 20 which may constitute a simpledisc arranged to berotated about a central axis coinciding with the axis of the inputconnector 12. The disc 20 roller.

carries a roller shaft 21 rotatably mounting an insulative roller 22eccentrically positioned in radially spaced, parallel relationship tothe axis of the disc. The arrangement is such that when the drivingmember 20. is rotated by the motor shaft 18, the roller 22 will revolveabout the central axis of the motor shaft to describe a circular locuswithin a central cavity 23 in the block member 11. The connector 12includes an inner stationary conductor 24 projecting centrallywithinthis cavity 23 along the axis of rotation of the disc 20 so that theroller 22 revolves in spaced, parallel relationship about thisstationary conductor.

Laterally movable towards the stationary conductor 24 are two switchingpistons in the form of insulative cylindrical members 25 and 26. Thesemembers are mounted 'for back and forth motion within bores 27 and 23respectively axially aligned with the output connectors 13 and 14 in theblock 11. The cylindrical members 25 and 26 are of insulating materialpreferably of a light plastic and are biased towards the stationarycenter conductor 24 by springs 29 and 30. Essentially, these mem bersserve as telescoping guides, respectively, for split sleeve contactorsincluding a split sleeve portion 31 and contacting head 32 for themember 25 and a split sleeve portion 33 and contacting head 34 for themember 26.

The sleeve portions 31 and 33 telescopically ride over the innerconductors 35 and 36 respectively of the output connectors 13 and 14.The outside diameter of each of the insulative cylindrical members 25and 26 is at least as large as the diameter of the circular locusdescribed by the roller 22 so that the roller 22 may engage the ends ofthe plastic members 25 and 26 in its travel about the stationaryconductor 24.

The operation of the lobing switch of Figure 1 will be clearlyunderstood by referring to Figures 2, 3 and 4. Figure 2 illustrates thesame position of the movable components as shown in Figure 1. In thisposition, it will be noted that the input connector 12 of Figure 1 hasits inner conductor 24 electrically connected to the inner conductor 36of the output connector 14 through the medium of the split sleeveportion 33 and contacting head 34. In this position, high frequencyenergy will be easily conducted from the input co-axial line 12 to theoutput co-axial line 14. The output connector 13, on the other hand,will be substantially completely isolated as a consequence of the largegap between the inner conductor 24 and the inner conductor 35 of thisoutput connector.

As the roller 22 on the shaft 21 moves in a counter clockwise directionas indicated by the arrow in Figure 2,

it will assume the position shown in Figure 3, the biasing spring 29urging the cylindrical piston member 25 and associated split sleeve 31in a direction to follow the In the position illustrated in Figure3, thecontact head 32 will engage the inner stationary conductor 24. By makingthe diameter of the roller 22 as indicated at d slightly less than thediameter of the stationary center conductor 24, contact between thecontacting head 32 and conductor 24 can be achieved prior to breaking ofcontact between the conductor 24 and the contacting head 34. 7

As the roller 22 continues in its revolving movement about thestationary center conductor 24, it will engage the end of thecylindrical piston member 26 urging this member to the right as shown inFigure 4 and thus breaking the connection between the contacting head 34and center conductor 24. In the meantime, the contacting head 32 andconductor 34 are retained in metal to metal engagement by the pressureof the biasing spring 29.

As the roller 22 continues in a counter clockwise direction from theposition in Figure 4 back towards the positions illustrated in Figures 1and 2, the contacting head 34 will make engagement with the centerstationary conductor 24 prior to separation of the contacting head 32. p

It will be evident that by rotating the disc 20 of Figure 1 veryrapidly, the roller 22 can be made to complete several hundredrevolutions per minute thereby achieving extremely rapid switchingbetween the input connector 12 and the two output connectors 13 and 14.Further, it will be evident that by making the diameter of the roller 22slightly larger, that is, larger than the external diameter of thestationary center input conductor 24, a breakbefore-make action can beachieved, the various discrete energy portions distributed to each ofthe output lines being separated bya small time gap in which no energyis passed to either line. At all events it will be evident as aconsequence of the described construction that equal portions of energywill be consistently delivered to each of the two output lines.Moreover, an excellent physical metal to metal contact will always beassured notwithstanding physical wear since the two contacts 32 and 34are constantly being urged towards the center conductor by the biasingsprings.

Preferably, the entire central cavity within the block 11 is filled witha dielectric oil as indicated at 37 in Figure 1 so that proper impedancematching, heat dissipation, and are quenching are assured. 7 Moreover,the continuous movement of the roller about the cavity serves to pick upthe oil and maintain all moving parts properly lubricated.

' The inner conductors 35 and 36 are tapered as shown so that only thehead portions thereof slidably engage the split sleeves 31 and 33 tominimize friction.

The metallic springs 29 and 30 themselves are designed so that when intheir expanded condition they form a proper impedance matching sectionof co-axial line with the tapered portions of the inner conductors. Onthe other hand, when these springs are compressed there results amis-matching of this'section so that additional isolation between thecenter conductor and disconnected output connector is provided.

To help minimize electrical noise as a consequence of possible chatterwhen metal to metal contact is made, the center conductor 24 of Figures1, 2, 3 and 4 may be modified as shown in Figure 5.

In Figure 5, the center conductor from the input coaxial connector isdesignated 38 and includes two diametrically opposite lateral slots 39and 44 cut from the top and terminating short of the lower end oftheconductor. Theseslots respectively accommodate secondary contacts in theform of metallic bands 41 and 42 secured within the lower ends of theslots and biased radially outwardly as shown. The top portions of thebands are bent, to horizontal positions, having a length equal to thedepth ofthe slots and terminating short of the end walls of the slots bya distancecorresponding to the radially protruding-distances ofthe-bands as a consequence of the radially outward bias.

By this arrangement, the contacting heads of the inner conductors willengage the bands prior to engaging the center conductor and then bothwill be engaged. Thus,

referring to Figure 6, the contacting-head 32 of the pis- In certainapplications, the roller 22 of Figures 1, 2, 3 Q

and '4, may be made of conducting material and the insulated cylindricalpiston members provided with conducting portions so that the roller willground or short circuit'the disengaged contacting head and thus furtherimprove electrical isolation. I I v I Referring to Figure 7, forexample, there is shown a conducting roller 43 mounted on the shaft 21.The cylindrical member for the inner conductor 35, split sleeve 31 andcontacting head 32, however, is modified to include in addition to aninsulated portion 44, a conducting band 45 engaging the spring 29 and incontact with the metallic block 11.

By the foregoing arrangement, the metallic roller 43 will ground thecontacting head 32 to the metallic block 11 through the conducting band45 and will thus short circuit the inner conductor of the disconnectedoutput coaxial line to its outer conductor.

From the foregoing description of Figures 1 through 7, it will beevident that the desired features of good impedance matching betweenconnected lines, good isolation between the connected and disconnectedlines, and a low noise level in the device are all realized.

While the embodiment of the invention described relates to the switchingof energy from an input co-axial line to only two output co-axial lines,it will be evident that the cavity 23 and both the stationary innerconductor 24 and the roller 22 could be modified in dimensions to allowother output co-axial connectors to be accommodated within the cavity 23and thus operated by the same roller actuating the switching pistonmembers 25 and 26. Such additional co-axial output lines and theircooperation with the principal driving structure is a meremultiplication of parts and will readily be understood to fall withinthe scope and spirit of the present invention.

Other modifications that fall within the scope and spirit of thisinvention will also readily occur to those skilled in the art. The highfrequency switching unit is, therefore, not to be thought of as limitedto the particular embodiment set forth for illustrative purposes.

What is claimed is:

l. A unit for switching high frequency electrical energy from an inputco-axial line connector between at least two output co-axial lineconnectors, comprising, in combination: a conducting block member havinga central cavity and oppositely directed bores extending from saidcentral cavity to opposite exterior sides of said block member, saidinput co-axial line connector having its outer conductor connected tosaid block and an inner stationary conductor projecting centrally withinsaid cavity, said output co-axial line connectors having their outerconductors connected to and forming a continuation of said bores andtheir inner conductors extending co-axially within said bores andterminating short of said stationary conductor; conducting sleevecontactors mounted for telescoping movement over said inner conductorsrespectively; biasing means urging said sleeve contactors towards saidstationary conductor; and driving means projecting into said centralcavity for alternately moving said sleeve contactors into and out ofengagement with said stationary conductor.

2. The subject matter of claim 1, in which said driving means includes aroller extending in a direction parallel to and radially spaced fromsaid stationary conductor; a driving member; and a motor secured to saidblock member and connected to rotate said driving member about an axiscoinciding with said stationary conductor, said roller beingeccentrically connected to said driving member so that said rollerrevolves about said stationary conductor to move said sleeve contactorsinto and out of engagement with said stationary conductor.

3. The subject matter of claim 2, in which said stationary conductorincludes diametrically opposite lateral slots; and conducting bandssecured in said slots and biased to protrude radially outwardly fromsaid slots to engage the head portions of said sleeve contactors priorto engagement.

4. The subject matter of claim 2, including cylindrical membersdimensioned for reciprocal movement in said bores and surrounding saidsleeve contactors for guiding said sleeve contactors in back and forthmotion, the diameter of said cylindrical members being at least equal tothe diameter of the circular locus described by said roller.

5. The subject matter of claim 4, in which said roller is conductive andouter portions of said cylindrical memhere are conductive so that whensaid roller engages one of said sleeve contactors it also engages theconducting portion of the corresponding cylindrical member toelectrically short circuit the corresponding inner conductor to whichsaid one of said sleeve contactors is connected to its outer conductor.

6. The subject matter of claim 3, in which the diameter of said rolleris less than the diameter of said stationary conductor whereby one ofsaid sleeve contactors engages said stationary conductor prior to theseparation of the other of said sleeve contactors from said stationaryconductor by said roller.

7. The subject of claim 4, including a casing structure covering saidmotor and hermetically sealed to said block member; and oil filling saidcentral cavity.

8. A unit for switching electrical energy from an input line between atleast two output lines comprising, in combination: a stationaryconductor for connection to said input line; two movable conductors forconnection to said output lines respectively, said movable conductorsbeing positioned on opposite sides of said stationary conductor formovement towards and away from said stationary conductor; biasing meansurging said movable conductors towards said stationary conductor; anddriving means including a roller mounted for revolving movement about anaxis coinciding with said stationary conductor and arranged alternatelyto move said movable conductors out of contact with said stationaryconductor, whereby electrical energy at said input line is alternatelyswitched between said two output lines.

References Cited in the file of this patent UNITED STATES PATENTS2,286,611 Farmer June 16, 1942 2,709,725 Bieber et al. May 31, 19552,814,696 Cockerham Nov. 26, 1957 2,816,198 Cherry Dec. 10, 1957

